On Fri, 8 Feb 2002 23:46:29 GMT, [EMAIL PROTECTED] wrote: >> What this doesn't address is why the tail of this particular airliner >> fell off while it was travelling at a comparatively modest speed. >> Anything over 250 kts would have been illegal at that altitude and >> would have been REALLY played up by the media. But the point is >> valid; the NTSB quizzed a bunch of pilots about Vne issues and >> discovered that most of them were clueless about the subject. > >Did they quiz the pilots about Vne? I thought I had read that the pilots they >interviewed were incorrect in their assumptions about rudder limiting features, >and that there did exist an opportunity to enter combinations of rudder >movements (specifically a series of opposite rudder commands) that could cause >structural failure in the rudder - even well below Vne. I read that the pilots >were unaware of this. Probably so were the designers. One would think that, >unlike a Bonanza, a modern commercial transport would limit the ability of the >pilots to damage their own aircraft via structural filters and limiters.
The A300 was the first Airbus design and isn't all that 'modern', first flight was 1972 which means design began back in the late 60's. The specific model involved was first flown in 1983. >Airbus >has had its share of problems with 'smart' FCS, though. I still remember the >video of that Airbus (A-300?) inaugural flight that plowed a section of forest >when trying to takeoff after a low-speed pass over the runway, when the FCS >insisted that the aircraft was landing and could not command the engines to >takeoff thrust. Wrong. It was an A320 where the display pilot (some time after 'first flight') switched off major protective modes of the FCS. He did this to show that he could fly the A320 'party trick' of a low, slow, high alpha pass with safety (due to FCS protection) manually. He couldn't He al edged that the engines didn't spool up as fast as they should have when he got into trouble. He also alleged tampering with the Flight Data Recorder record. This ignores the fact that CVR sound, sound on a spectators video and the FDR all agree. And what they agree on is that the engines ran up just as expected - until the point at which they began to eat treetops. Even if there had been a problem with engine spool-up that wouldn't alter the fact that flying a low speed, low altitude, high alpha pass in a large airliner that has significant parts of the FCS disabled is not a good idea. >Wasn't there also an angle to this story where a failed composite structure of >the rudder was involved in a previous incident on the same aircraft, or that >the failed part was actually an illegally repaired and used part? This is what has been _speculated_ upon widely in the press over here. here is what the NTSB actually say: http://www.ntsb.gov/Pressrel/2002/020115.htm They also make a concrete recommendation based on interim results: http://www.ntsb.gov/Recs/letters/2002/A02_01_02.pdf The key bits are: / ...flight 587 twice experienced turbulence consistent with / encountering wake vortices from a Boeing 747 that departed JFK / ahead of the accident aircraft. ... ...During and shortly / after the second encounter, the flight data recorder (FDR) on / the accident aircraft recorded several large rudder movements / (and corresponding pedal movements) to full or nearly full / available rudder deflection in one direction followed by full / or nearly full available rudder deflection in the opposite / direction. / .... / Preliminary information based on FDR data and an analysis of / the manner in which rudder position data is filtered / by the airplane?s systems indicates that within about 7 / seconds, the rudder traveled 11deg right for 0.5 second, / 10.5deg / left for 0.3 second, between 11deg and 10.5deg right for about / 2 seconds, 10deg left for about 1 second, and, finally, 9.5deg / right before the data became unreliable. / .... / Preliminary calculations by Safety Board and Airbus engineers / show that large sideloads were likely present on the vertical / stabilizer and rudder at the time they separated from the / airplane. Calculations and simulations show that, at the time / of the separation, the airplane was in an 8deg to 10deg / airplane nose-left sideslip while the rudder was deflected / 9.5deg to the right. / / [MY EMPHASISIS] Airbus engineers have determined that this / combination of local nose-left sideslip on the vertical / stabilizer and right rudder deflection produced air loads on / the vertical stabilizer that could exceed the airplane's / design loads. / [/MY EMPHASISIS] / / The Board notes that, at the time the vertical stabilizer and / rudder separated from the airplane, the airplane was flying at / 255 knots indicated airspeed (KIAS), which is significantly / below the airplane?s design maneuvering speed of 273 KIAS. Rick -- David Farrent and Dougie O'Hara on the Cold War role of the ROC: 'What a world of sorrow is hidden in those few words - "[Post attack] crew changes would have been based on crew availability."' _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
